How to mass refresh textures and say blender to look for them at different location
you can  do that using python script to alter the path of every image located in the older folder to be looked for in the new one; the nodes will automatically be updated after this :

import bpy

images = bpy.data.images  

for img in images :
    if img.source == 'FILE' :
         img.filepath = img.filepath.replace('\\old_folder\\','\\new_folder\\')
         img.reload()